Photography of very small objects has always been difficult and complicated. It involves all the usual problems of photography plus the problems of using a microscope to select an area to be photographed. The microscope is a complicated optical instrument requiring provision of special means for illumination to provide an image for visual observation and finally of means for then transferring the image of adequate brightness to a suitable camera. A special problem is that lighting conditions for visual observation are not suitable for photography except for a fairly long exposure, which is not possible for a moving object or when vibration is encountered. It is, therefore, often necessary and generally desirable to use a flash lamp for the actual photography, but this is greatly complicated by the need for providing dual illumination systems, both of which have to comply with quite specific optical requirements and which have to replace one another without essential change of the selected optical conditions, such as direction and uniformity of illumination, accurate focusing, and the like.
Efforts to simplify and automate the procedure and equipment have not been particularly successful, although excellent results have been obtained by use of the inconvenient, bulky, and cumbersome equipment heretofore known. Such efforts have included use of high intensity illumination such as xenon arcs, either with conventional mirrors and condensers, or combined with a fiber optic "light pipe" to space the light source from the microscope and prevent the heat of the lamp from damaging the microscope or the specimen being photographed.
Other attempted solutions have included various arrangements of dual light sources. One light source would be a continuously illuminated focusing lamp, such as an incandescent tungsten filament lamp, for scanning of the object, selecting the desired field of view, and focusing. It would then be physically replaced by a flash lamp, and its associated electrical equipment. The consequence has been that the operator has had his microscope instrument surrounded by inconveniently located heat-generating equipment, requiring a carefully scheduled sequence of manual operations in order to produce each photograph.
The principal objects of this invention, accordingly, are to simplify the mechanical equipment required to be manipulated, minimize the cluttering of the operator's work space, and at the same time to automate the procedure so that photomicrographs can be obtained easily and quickly and with reasonable assurance of success with each photographic exposure.